I've often seen two things conflated when it comes to cancer & Mars. The first is that if we send people on a one-off return mission their lifetime risk of can

I've often seen two things conflated when it comes to cancer & Mars. The first is that if we send people on a one-off return mission their lifetime risk of cancer will increase by X%. This is obviously a concern, but as others here in the thread have mentioned we could get people willing to accept the risk. The second is that if people stay on Mars for generations you have the risk of cumulative damage to DNA over generations. Now it's not just a problem that instead of living to 80 you die of cancer at 60, but rather that after N generations the population's DNA might be damaged past repair.